I. Field of the Invention
The present invention relates to a turbine airfoil construction such as a turbine blade or turbine nozzle vane.
II. Description of the Prior Art
Turbine airfoils, such as turbine blades and turbine nozzle vanes are typically constructed by casting the airfoil from metal or ceramic. Many of the previously known airfoils include a hollow interior and cooling air is circulated through the interior of the airfoil in order to cool it. This cooling air flow is ultimately exhausted into the gas stream through openings formed in the airfoil.
Under normal operating conditions, the turbine airfoil is subjected to extremely high temperatures, often in excess of 2,000.degree. F. Since the interior of the airfoil is cooled, very high thermal gradients are formed across the turbine airfoil during the normal operation of the turbine engine. These high thermal gradients oftentimes crack the airfoil and necessitate prolonged and expensive repair of the turbine engine.